Refrigerating machine of the combined compression-absorption type



April 10, 1951 R. BERNAT ET AL 2,548,699

REFRIGERATING MACHINE OF THE COMBINED COMPRESSION-ABSORPTION TYPE Filed Oct. 29, 1945 2 She ets-Sheet 1 fwwlidzz Filed Oct. 29, 1945 2 Sheets-Sheet 2 April 10, 1951 R. BERNAT ET AL 2,548,699

REFRIGERATING MACHINE OF THE. COMBINED COMPRESSION-ABSORPTION TYPE Patented Apr. 10, 1 951 UNITED STATES PATENT OFFICE.

Raoul Bernat and Henri Bernat, Bordeaux, France Application October 29, 1945 Serial No; 625,340 In France September 8, 1943 8 Claims. (o1. 62-119) It is known to combine in one refrigerating machine the compression method and the absorption method, also called afilnity method,-and to produce an oversaturated solution of the cooling fluid by causing the latter to be absorbed by the liquid solvent under a pressure exceeding that of the evaporator.

According to this invention, the absorber is only in part under a super pressure and compressing is achieved between an absorber part in which no pressure obtains and another part which is under a super pressure, using conveniently therefor a compressor for the gases and a pump for forcing the solution. 7

There may be advantageously provided a vessel in which the gaseous and liquid portions may be separated from each other.

Following absorption, the solution is directed, as usual into the boiler, or still in order to cause the evolution of the dissolved gas. This evolution is effected in two steps, the liquid being partially weakened in a first boiler and passing, then, into a seond boiler, heated at higher temperature.

Preferably:

(a) The boilers, or stills consist of double walled tubes with external heating;

(b) The cooling and heating fluids flow in opposite directions in said tubes;

(c) The cooling fluid enters said tubes at the lower part thereof;

(d) 'To the vapour which has been used to heat the relatively high temperature boiler are added exhaust gases of an engine the counter pressure of which may be controlled by or in accordance with the temperature desired in the relatively low temperature boiler;

(e) The gas evolved in the high temperature boiler is introduced into the other boiler;

(f) The gas produced in both boilers is led into one or several rectifiers;

(g) The mist evolved in the rectifier or rectiing example on the accompanying drawings in fiers are returned into the low temperature which:

Fig. l is a diagrammatic flow View of a first embodiment,

Fig. 2 is a similar View of a modification.

The refrigerating machine shown in Fig. 1 comprises two boilers, or stills, 2, t, the former being at a lower temperature than the latter; two rectifiers 3, t, the first of which, of the platetype, is arranged in the upper part of the still 2; two condensers, I, '9, separated from each other by an accumulator 8; an evaporator l8;

two absorbers l i, it respectively at low and high pressure; a receiver 52 connected with the outlet of absorbers ll; a pump is and a compressor Hi, both arranged in parallel pipes connected with outlets of receiver l2 and respectively adapted to force the liquid into theabsorber l5 and to compress the gas; a pump it, connected with the outlet of absorber l5, for forcing the liquid into the rectifier 5; an interchanger l'l, heated by the weakened liquid from still a, for heating, in turn, the strengthened liquid from the rectifier 6; and two sets of coils 5 and I respectively arranged in the stills i .and 2, the former 5 being fed with vapour entering at it and the latter being fed with a mixture of said vapour from coil 5 and exhaust gases enter-- ing at v id, the mixture beingefiected at (58. Be-- sides, the machine comprises a number of connecting pipes 2!] to 25, 2'? .to 32 and 3! to 42, the purpose of which is given hereafter. Cocks 25, 33 and 43 are provided for controlling the rate of flow in the corresponding connecting pipes.

The operation is as follows:

When starting, the stills 2 and A are under a" pressure. of 11 kgs. (per square centimeter) and contain an oversaturated ammonia solutiom'for' instance 560 kgs. of gas ammonia and 460 "kgs. of water. vapours ata temperature of 9i? C. and by the vapour flowingfrom the coils. 5, whereas the still i is heated by steam under such a high pressure that the temperature of the ammonia solution is brought to 140 C. By being heated at C. in the still 2, under a pressure of 11 kgs., the solution gives up 258 kgs. of gas ammonia. In proportion as it becomes weaker, said solution passes by the-pipe 36 into the still 4, in which it is heated to C. under the same pressure, i. e., 11 kgs., and in which it further gives up 177 kgs; of gas ammonia. The latter flows by wayof pipe 2!} into the still 2, in which its temperature is brought back to 90 C. Mixing of gas ammonia from the stills 2 and 4 causes a first rectification,

The still 2 is heated by exhaustand a second rectification is then caused by the mixture flowing in the rectifier on whose plates descend the mists flowing from the rectifier 6 through pipe 42 and the rich solution, the socalled strong aqua conveyed to said rectifier 3 by way of the pipe 4!. The gas flows through pipe 2| into the rectifier 6 in which the drying thereof is completed. The gas thus dried flows into the condenser i in which it is liquefied. The liquid ammonia passes by way of the pipe 23 into the accumulator 8, from which it flows through pipe 25 into the subcooler 9, and then, through pipe 241, into the evaporator I0, in which it volatilises, giving up calories. The cool ammonia gas thus formed escapes by way of pipe 2? and enters the cooler 9, in which the liquid ammonia is cooled thereby. The cooled ammonia gas discharged from the cooler 9 is led by 4 d after passing through the interchanger i'i.

Since the absorption in H is not complete, the mixture of liquid and gas passes through the pipe 2Q into the receiver 52 in which the gas, and the liquid are separated from each other. The partially concentrated ammonia solution is suctioned into pipe 36 by pump I3, while the ammonia gas flows through pipe 34 into compressor i4, which delivers it under pressure, by way of pipe 35, into the high pressure absorber l5, joining therein the partially strengthened ammonnia solution driven into pipe 32 by pump 53. i dissolving of said ammonia gas in said solution is completed. The enriched solution, or strong aqua, is then suctioned into pipe 38 by pump [6, which forces it through pipe 39 into the tubes of rectifier 6. Said strong aqua cools the gas from the still 2 flowing outside of said tubes and passes then through pipe 43 into the tubes of heat exchanger H, in which it is reheated by the weak aqua flowing from pipe 3! into the space outside said tubes. The partially reheated strong aqua issuing from the tubes of exchanger ll flows through pipe 4| into the top part of rectifier 3, and the cycle is repeated.

It will be noted that the still 2 may be heated to the temperature of 100 C. or 110 C., for example, in order to reduce the amount of gas to be produced in still 4, by simply increasing the vapour pressure.

Obviously, the present invention is not limited to the described example. Thus, for example:

(a) The stills 2 and 4 may be replaced by a single still or boiler, though this has the drawback of causing sometimes a turbulent boiling.

(b) Said stills 2 and 4 may also be designed in the manner shown in 2, in which the members similar or corresponding to those of Fig. l are designated by the same numbers. As shown in Fig. 2, the boilers 2 and 4 consist of double walled tubes and 5. The vapour entering at 55 flows into the outer wall or annular space of tubes 5, is then conveyed by means of pipe l'i, under the control of a cook 43, to the point is, where it will eventually mix with exhaust gases from pipe 44; this heating fluid flows in the annular space of tubes i and escapes through pipe as. The strong aqua is admitted by a pipe 193 into the lower part of the inner wall of tubes I and flows upwardly in said tubes to be progressively heated therein, the mixture of liquid and gases passing through a pipe it into a separator I01, from which the gases escape through the plate rectifier 3. The liquid being partially In said absorber.

freed from the gases is led through pipe 30 into the lower part of the inner wall of tubes 5, in which it is submitted to the progressing heating action of the vapour; said liquid is thus progressively weakened, and the mixture of liquid and gases passes through a pipe 152 into the separator cm, the gases entering the rectifier 3 through pipe 26, whereas the weakened liquid is led by way or" pipe 3| into the exchanger H.

(c) There may also be provided between the receiver I2 and the compressor M a rotary or paddle rare-compressor, preferably of the multicellular type, whose suction side will thus be connected with the evaporator H3 and whose delivery side will be connected with the suction side of compressor M. This permits of increasing the output of the described plant.

We claim:

1. A refrigerating machine of the combined compression-absorption type comprising means for heating a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and said mixture of dissolved fluid and solvent into said second absorber, said means for separating said undissolved fluid from said mixture of dissolved fluid and solvent being a receiving vessel and said means for forcing said undissolved fluid and said mixture of dissolved fluid and solvent being located between said vessel and said second absorber.

2. A refrigerating machine of the combined compressionabsorption type comprising means for heating a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and said mixture of dissolved fluid and solvent into said second absorber, said forcing means including a compressor for the undissolved fluid and a pump for the dissolved fluid and solvent.

3. A refrigerating machine of the combined compression-ahsorption type comprising means for heating a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximatelyequal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and said mixture of dissolved fluid and solvent into. said second absorber, said forcing means including a pre-compressor and a compressor for said undissolved fluid and a pump for said dissolved fluid and solvent.

i. A refrigerating machine of the combined compression-absorption type comprising means for heating a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and said mixture of dissolved fluid and solvent into said second absorber, said heating means comprising a first boiler to which is conveyed the mixture from said second absorber and a second boiler having a temperature higher than said first boiler and means for conveying the liquid portion of the mixture from said first boiler to said second boiler.

5. A refrigerating machine of the combined compression-absorption type comprising means for heating a mixture of liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and said mixture of dissolved fluid and solvent into said second absorber, said heatin means comprising a first boiler to which is conveyed the mixture from said second absorber and a second boiler having a temperature higher than said first boiler and means for conveying the liquid portion of the mixture from said first boiler to said second boiler, said boilers being constructed of double walled tubes and the mixture in the inner portion of said tubes flows countercurrent to the flow of heating fluid in the annular portion of said tubes.

6. A refrigerating machine of the combined compression-absorption type comprising means for heatin a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separatin that fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for foreing said undissolved fluid and said mixture of dissolved fluid and solvent into said second absorber, said heating means comprising a first boiler to which is conveyed the mixture from said second absorber and a second boiler having a temperature higher than said first boiler and means for conveying the liquid portion of the mixture from said first boiler to the said second boiler, said boilers being constructed of double walled tubes and the mixture in the inner portion of said tubes flows counter-current to the flow of heating fluid in the annular portion of said tubes, said mixture enters said tubes at the lower portion thereof.

7. A refrigerating machine of the combined compression-absorption type comprising means for heating a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an. evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undissolved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and aid mixture of dissolved fluid and solvent into second absorber, said heating means comprising a first boiler to which is conveyed the mixture from second absorber and a second boiler having a temperature higher than said first boiler and means for conveying the liquid portion of the mixture from said first boiler to said second boiler, said boilers being constructed of double Walled tubes and the mixture in the inner portion of said tubes flows countercurrent to the flow of heating fluid in the annular portion of said tubes, said first boiler being heated by the heating fluid from said second boiler and by the exhaust gases of an engine.

8. A refrigerating machine of the combined compression-absorption type comprising means for heating a mixture of a liquid solvent and cooling fluid, means for separating said solvent and fluid, an evaporator, a first absorber having a pressure therein at most approximately equal to that in said evaporator, a second absorber having a pressure therein higher than that in said evaporator, means for separating said fluid undis solved in said first absorber from the mixture of dissolved fluid and solvent, means for forcing said undissolved fluid and said mixture of dissolved fiuid and solvent into said second absorber, said heating means comprising a first boiler to which is conveyed the mixture from said second absorber and a second boiler havin a temperature higher than said first boiler and means for conveying the liquid portion of the mixture from said first boiler to said second boiler, said boilers being constructed of double walled tubes and the mixture in the inner portion of said tubes flows countercurrent to the flow of heating fluid in the annular portion of said tubes, a rectifier through which the gaseous portion of the mixture passes.

RAOUL BERNAT. HENRI BERNAT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 461,233 Butler Oct. 13, 1891 462,551 Hill Nov. 2, 1891 925,625 Day June 22, 1909 967,992 Starr Aug. 23, 1910 1,109,923 Hiller Sept. 8, 1914 1,171,305 Beadle Feb. 8, 1916 

